Cutting



June. 27, 1939.

A. J. JACOBSEN CUTTING Filed Jan. 10, 1938 2 Sheets-Sheet l June 27,1939. J. JACQBSEN 2,163,687

CUTTING Filed Jan. 10, 1958 2 Sheets-Sheet 2 Patented June 27, 1939UNITED STATES CUTTING Arthur 1.? Jacobsen, Chicago, 111., assignor toBucyrus-Monighan Company. Chicago,

corporation of Illinois Application January 10,

1 Claim.

This invention relates to the abrasive cutting of especially hardmaterials andis directed mainly to the cutting of the hardest ofmetallic compositions such as used in tools and in recently developedmagnetic alloys.

In work of that nature, it is common practice at the present time to dothe cutting with thin composition disks carrying abrasive particles inbonds of various substances of the nature of resinous compounds orvulcanite. The disks are thin, measuring about one-sixteenth of an inchin thickness, while often being approximateh sixteen inches in diameter.The cutting' disks are comparatively fragile, may be flexed, and aresubject to softening by the action of heat. Nevertheless such disks arehighly successful in cutting hard material relative to other tools inthat work. The disks failwif glazed or not cleared of cut particles andallowed to become heated or when subiect to unbalanced lateral pressurewhen at work. -It is customary when operating these disks to deliver acooling fluid to the disks or to run them in 'a coolant. But with allthe present set-ups or methods of operating such cutting disks known to5 applicant, there are decided needless limitations as to theirperformance.

'I'he present invention is intended to improve the operation of the typeof cutting disks above specified and to cause them to do better work inless time than heretofore and enable them to successfully cut someextremely hard materials which could not\be cut satisfactorily by usualmethods.

A purpose of the invention is mainly to cut hard tempered metals withoutthe heating of the metal at the cut sufficiently to affect the temper orcolor thereof, and to keep the tool protected by a proper scouringaction of the coolant. A further purpose of the invention is to reducethe cost and time generally required for cutting hard materials and toobviate the necessity of any further treatment of the cut surface suchas by grinding or polishing. These objects are accomplished by means ofa different method of applying a cooling fluid to a cuttingdisk and tothe cut surfaces of the material operated upon, which method includescoordination of the velocity and direction of delivery of the coolingfluid with thespeed and direction of rotation of the disk, controllingtemperature of the fluid according to the work performed by the disk,using the fluid as a hydraulic cushion. for the disk, balancing of thefluid im-' pact pressure upon the opposite sides of the disk, and bymeans of a construction as illustrated in the drawings, wherein:

1938, Serial No. 184,165

Figure 1 is afront elevation of the cutting machine with part'of itshousing shown broken away. i

Fig. 2 is a longitudinal section through the cutter spindle bearings, asindicated by the line 2-2 on Fig. 1.

Fig. 3 is a sectional detail through the cooling fluid nozzles andcutting disk, as indicated by the line 3 on Fig. 1.

Fig. 4 is an enlarged fragmentary view of the cutting disk showing thelocation of a cooling nozzle and work operated upon with respect to thedisk. s

Fig. 5 is an enlarged *ragment in section of a cutting disk and articleperated upon.

Fig. 6 is a perspective view of one of the cooling fluid nozzles.

The successful cutting of extraordinarily hard metals is rarely attainedexcept at high cost and without much speed. Dry cutting, and what isknown as immersed cutting, or cutting while the disk is cooled by merelyflowing or spraying the cooling fluid on to the disk without controlledvelocity, temperature and form of the fluid streams generally results intoo much heating at the cut surface, which changes the character of themetal at that point as evidenced by a change in color. However, so faras known, the cutting of very hard metals or alloys must be doneabrasively, and then to do exceptionally good'work provision should bemade to properly protect the disk and the material operated upon fromthe effects of overheating.

The improved method of cutting herein disclosed is presumed 'to benovel'in the manner of application of a cooling fluid to the well-knowncomposition abrasive cutting disks and to the cut surfaces of materialoperated upon.

In the performance of cutting operations of the character hereinreferred to, the chief considerations in addition to successfulperformance in cutting without drawing the temper of the material oroverheating it, are maintaining a low cost per out in regard to the timerequired, and the preservation of. the cutting tool. It is essential tohave substantial bearings for the-cutting spindle or some certainprovision for running the disk true with all lateral pressure thereon.absolutely counterbalanced or equal on the two sides of the disk.Another absolute essential for accurate work and .long life of the disksis to keep the disks entirely free from out particles becomingembeddedtherein. So far as known to applicant, the short life and imperfect workhad in some cases and the entire absence of capacity for some cuttingoperations according to prior methods, is due to particles of the cutmaterial becoming embedded in the disk. This causes the disk to glaze atits sides, wear with rounded edges, and to vary in thickness, with theresult of excessive wear on the disk, imperfect work and a short life ofthe disk.

It is found that such objections may be entirely overcome by applyingthe cooling fluid equally on both sides of the disk and with such form,velocity, temperature and direction toward the disk and into the cutthat the particles cut from the work are driven clear of the disk.

With the machine herein illustrated, ribbons of water of equal volumeand velocity are directed into contact with and along the sides of thedisk in its direction of rotation along the cut entering areas of thedisk prior to'such areas reaching the cut. The rate of flow of thecooling. wateras it leaves the nozzles is commensurate with theoperating surface-speed of the disk.

The intention of the invention is to render successful high-speed,abrasive cutting-operations and to do this the cooling fluid isdelivered in the direction of rotation of the cutting disk at at leastapproximately the same speed, but the principle followed out isapplicable to lower cutting speeds. Also the rate of flow of the coolingwater may be somewhat less than the adjacent surface speed of the diskfor the reason that the drag of the disk on the water causes the waterto approximate the speed of the disk. The coolant must be underappropriate pressure according to the travel of the cutting surface infeet per minute. The drag of the disk alone is insufficient to effectthe necessary motion of the coolant as is proved by failures when thedisk is merely immersed in a relatively stationary body of Water. Thewater is then troughed by air drag and fails to prevent undue heating ofthe disk. From applicants experience, the velocity of the water underits own pressure should be at least 75% or 80% of the disks speed.

"As an example of successful cutting by the improved method of thehardest of tool steels or magnetic alloys under conditions of relativelylow disk speed and minimum water velocity, a fourteen inch diameter diskis driven at 2300 R. P. M.

The water velocity as it leaves the nozzles is 6,425 feet per minute andthe speed of the disk midway between the sides of the nozzles is 7,225feet per minute. The depth of the cut is -l2- of an inch and thematerial is removed at the rate of approximately 1 cubic inches perminute. The water is cooled somewhat below the normal room temperature.

The resulting cut is clean without injury to the material operated uponand the cutting disk comes through clean with remarkably little wear.According to this invention, when the speed of the cutting disk isincreased, a corresponding increase in the water pressure andcorresponding reduction in the water temperature is made.

With the older methods as comnonly practiced at this time, where noparticular attention is paid to the water pressure or its temperature,or as is common by performing the cutting operation while the tool isimmersed in the cooling fluid, it will be found that not only is the material operated upon injured by the heat but that there is much greaterwear on the cutting disk. The cooling fluid or air is then merelydragged by the disk through the cuts and fails to perform its functionwith maximum e'fliciency.

The construction illustrated in the drawings is designed for the purposeof avoiding the causes of failure, such as result from merely flowingthe cooling fluid onto the disk or operating the disk when immersed inthe cooling fluid. Such customary methods often result in overheatingand ruining of the disk.

The new construction causes the fluid streams to travel in ribbon formtoward the cutting disks and in the'direction of rotation of the disksat a velocity and temperature consistent with the speed and abradingwork performed. The article operated upon is slowly fed againstfrictional retarding means in a line tangential to the cutting disk andin the direction of its rotation. Y

The construction illustrated includes a heavy machine frame structure Iextending upwardly from the base 2 and including a fixed motor support3. The cutting disk 4 is fast to a spindle 6 having bearings l and 8 ina tubular element 9 longitudinally/adjustable in frame member I.Provision is made for axial adjustment of tube 9 so that the precise,desired location of cutting disk 4 may be' determined with reference toa support ID for work operated upon. For such reason the supports II fortube 9 are made in the form of clamps in order to hold the tube in anydesired position. The support 3 for the motor and the pump is carried bytube 9 and moves with it and the distance between belt pulley centersremains fixed.

Support In is mounted upon a table top [2 which is vertically adjustableon a machine frame I by means of a screw connection l3 with frame I.Screw I3 is operated through beveled gear connections It with a shaft l5intended for rotation by means of a crank handle. Different types ofwork supports 10 may be clamped to table I! and fit the slots l6therein.

The work support ID as shown in Fig. 2 carries pressure plates l8 forfrictionally engaging articles operated upon. The contact pressurebetween these plates on the articles is determined on springs I 9, whichsprings are compressed more or less by the bolts 20.

The articles operated upon are-fed along sup-' port It by means of ahydraulic ram 2|. Details of this ram and the control means therefor areomitted from the drawings, as .it constitutes a customary feed meansfrequently used and is arranged for a slow forward feed and a quickreturn. Articles operated upon travel to the ram plunger by gravitythrough an inclined chute 22.

The lowermost article in the chute rests on'top of the ram and drops infront of the rain on the return stroke thereof.

The motor 23 for driving the machine has a belt connection 24 withpulley 25 on spindle 6 and also a belt connection 26 to a fluid pump 21for supplying fluid under pressure to nozzles 29. One nozzle is locatedat each side of the cutting disk 4 and is formed as illustrated byFigures 3.

and 6, with a restricted but wide or flaring out-'- let 29 and adeflecting wing 39.

The nozzles serve to direct a ribbon-like band of cooling fluid to eachside of the cutting disk toward the working portion of the disk. Thedirection of the cooling fluid is toward the cut in the direction ofrotationof the disk.

The direction of the flow of the fluid is first diagonally inward towardthe disk, as illustrated by Fig. 3 and its course is somewhat changed bythe drag of the disk as indicated in Fig. 4.

The temperature, direction and velocity of flow of the cooling fluid iscritical with reference to the speed of the disk for the cutting of thehardest metallic substances.

It is clear from experience in this character of I ture and velocity ofthe cooling streams according to the speed and work performed by thecutter, it is easy to provide the correct conditions for cutting anyknownmetal without injury to or changing the'character of the metal. If,with a given metal of known hardness, a cut may besuccessfully performedat 2500 R. P. M. of the spindle, at a water velocity substantially equalto the feet per minute speed of the disk and a fluid temperature of F.,then to cut a harder metal successfully at the same spindle speed, thetemperature of the coolingfluid is decreased. But if the spindle speedis increased, then the pressure on the cooling fluid is increased andits temperature is lowered accordingly.

With that method of operation, the wheel may remain clean and itscutting edge is not worn rounded outwardly but substantially flat orslightly concave as illustrated in Figure 5.

The fluid delivered to the cutting disk through nozzles 28 is cooledbelow normal water or room temperature in the settling tank 3| fromwhich the fluid is lifted through a conduit 32 by the pump- 21. From thepump the fluid passes through conduit 33 to the nozzles.

The cutting disk 4 is enclosed by a casing 34 and a door 35, except forthe slot 36 at the bottom between the casing and the door through thecooling fluid is maintained, irrespective of the amount of heatdeveloped by the work performed.

Except for the formation of nozzles 28, and perhaps particulararrangement of the friction elements l8 of the stock feed means,individual structural features of this machine are in principle old inmany machine tools. The method of forming the cut with the assistance ofbandlike jets on opposite sides of the disk and at a particulartemperature, angle and velocity with reference to the speed of the diskas assumed to be new.

In the operation of the construction, disk 4 is driven at a 'speedproportional to thespeed of pump 21 from the same source of power motor23.

F Thus the speed of the cutting edge of the disk is proportional to thepressure and volume of water pumped.

The rate of travel of the fluid projected on both sides of the disk fromnozzles 28 is intended to approximate that of the cutting edge of thedisk. The fluid also travels with and across the cutting edge of thedisk through the cut and at the temperature required to keep the diskcool according to the work performed.

The fluid has the usual function of removing heat and cut particles fromthe disk and from the articles worked upon. The fluid enters the cut andwashes around it and is successful in preventing any of the cutparticles becoming embedded in the disk.

A very common fault in abrasive cutting is due to cut particles adheringto the disks and crowding the disks in the cut. The disk is therebydulled and increases in thickness to the point of jamming in the cut andburning the metal.

When that occurs, the cut cannot be perfect and the sides of the disktake an excessive workload, Also the edge of the disk becomes roundedand the diskis less likely to remain rotating parallel to an absoluteplane at right-angles to its axis.

I claim:

The method of cutting with a thin, flexible abrasive disk which consistsin rotating the disk and causing its edge to contact with the materialto be out while projecting independent fluid streams in ribbon form, oneto each side of the disk'in the direction of rotation of the disk andtoward the cutting edge thereof, projecting said streams at equalangles, rates, and velocities, to the sides of the disk and at avelocity to cause the fluid to travel with the disk and into the out at,at least approximately, the peripheral speed of the disk. I I ARTHUR J.JACOBSEN.

